Britney and Christina came out around the same time and most people in the world/atrl consider britney a legend but i don't see much people saying the same for christina. What is christina's biggest moment/peak? Is she a legend or is she underrated?
Christina Aguilera is an undeniable icon with a great shot at being a legend. She needs to find a little more success and innovate more but she seems bent on making a huge comeback and I think it will really cement her place.
I wouldn't say legend - simply because her career isn't as long as say Madonna, Paul McCartney, Michael Jackson, Whitney Houston, Cher etc. She is an undisputed icon though. I do believe that a more successful era would help her along though (without being shady).